Balance Sheet Components Regulatory Assets and Liabilities (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Current Regulatory Assets [Member]
Regulatory Assets and Liabilities [Line Items]
Price risk management	$ 34	$ 36
Pension and other postretirement plans	0	0
Deferred income taxes	0	0
Deferred broker settlements	8	12
Debt reacquisition costs	0	0
Deferred capital projects	11	16
Other	2	2
Total regulatory assets	55	66
Noncurrent Regulatory Assets [Member]
Regulatory Assets and Liabilities [Line Items]
Price risk management	123	140
Pension and other postretirement plans	189	194
Deferred income taxes	78	76
Deferred broker settlements	0	1
Debt reacquisition costs	16	17
Deferred capital projects	19	18
Other	23	18
Total regulatory assets	448	464
Current Regulatory Liabilities [Member]
Regulatory Assets and Liabilities [Line Items]
Asset retirement removal costs	0	0
Trojan decommissioning activities	0	0
Asset retirement obligations	0	0
Other	2	1
Total regulatory liabilities	2	1
Noncurrent Regulatory Liabilities [Member]
Regulatory Assets and Liabilities [Line Items]
Asset retirement removal costs	762	747
Trojan decommissioning activities	42	41
Asset retirement obligations	39	39
Other	56	38
Total regulatory liabilities	$ 899	$ 865